My definition of clear (observable) is pretty generous.
If there’s a half hour spell between the clouds, that’s a clear night; if it’s cloudy enough to make the constellations hard to see, but the Moon is about, it’s clear.
Milky, humid skies that make deep-sky observing impossible, there are other things to look at, so it’s a clear night. Transparent skies with the Jet Stream overhead – happens quite often – I can look for hazy fuzzy objects, so it’s clear.
On the other hand, there will be times when it’s been clear but I haven’t noticed it. I have to admit that I don’t constantly watch the weather outside for a chance, and I do sleep too. In such cases it’s not a clear night.
Ten minutes or a whole night – or day if it’s solar… I observe the Moon during the day too – can be used to do some observational astronomy. It’s clear more than you think, even without radio astronomy.